The purpose of this study is to investigate the effects of the loss of muscle mass associated with aging (sarcopenia) on thermal balance and thermoregulatory responses to a cold environment. Older individuals are more at risk for hypothermia than younger individuals. One possible explanation for this increased risk may be decreased muscle mass (fat- free weight). Therefore, the aim of this study is to compare the thermoregulatory responses of older individuals with different fat free weights to a cold stress.